Atlas Copco Desiccant Air Dryers for Superior Productivity CD+ series (25-1400 l/s, 53- 2968 cfm) / BD+ series (100-3000 l/s, 212-6360 cfm)
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A dry compressed air system is essential to maintain the reliability of production processes and the quality of end products. Untreated air can cause corrosion in pipe work, premature failure of pneumatic equipment, and product spoilage.
How does a desiccant dryer work? Wet air passes directly through the desiccant medium which adsorbs the moisture. The desiccant medium has a finite capacity for adsorbing moisture before it must be dried out, or regenerated. To do this, the tower containing saturated desiccant medium is depressurized and the accumulated water is driven off. How this happens depends on the type of desiccant dryer: Heatless dryers use only compressed air as a purge. Blower purge dryers use a combination of air from an external blower, heat and minimal compressed air.
The drying process Wet compressed air flows upward through the desiccant which adsorbs the moisture, from bottom to top (1).
Switching After regeneration, the functions of both towers are switched (3).
The regeneration process
Selecting the right desiccant dryer for your application
Why desiccant dryers? Desiccant dryers or twin tower dryers consist of two towers filled with desiccant such as activated alumina or silica gel. While one tower is drying compressed air, the other is being regenerated. Desiccant dryers can achieve dewpoints of down to -40°C/-40°F and -70°C/-100°F. Three types of desiccant dryer are widely used throughout industry: heatless, heated purge and blower purge.
Lifecycle cost Desiccant dryer selection should be based on the required dewpoints and the cost of energy required to operate the dryer, and not only the initial capital cost. The energy costs are heavily dependent on the way in which the desiccant is regenerated. The illustration compares the lifecycle cost for three types of desiccant dryers sized to dry 550 l/s / 1160 cfm.
The heatless desiccant dryer is the most expensive to operate because of the high amount of compressed air that is consumed for purging during the regeneration cycle. Typically, 15% of the rated flow capacity of a heatless dryer is consumed as purge air. Although the cost of operating this type of dryer is high, the heatless type is often selected because of its simplicity and reliability.
Site conditions The selection of a desiccant dryer is also determined by the site conditions in which it has to operate. Desiccant dryers are particularly important in remote areas or hazardous sites where the atmosphere may contain explosive gases and powders, and in applications where the inlet air temperature is high. In such extreme environments, heatless desiccant dryers are preferred due to their simple design.
Heatless desiccant dryers:
Dry air from the outlet of the drying tower is expanded to atmospheric pressure and sent through the saturated desiccant, forcing the adsorbed moisture out (2) (4).
After desorption, the blow-off valve is closed and the vessel is re-pressurized.
Cooling Zero purge: After the heating, the hot tower desiccant is cooled.
Cooling is done by sending air from the hot vessel over a cooler and back into the hot tower, from bottom to top.
Purge: After the heating, the hot tower desiccant is cooled. Cooling is done by expanding dry compressed air from the outlet of the adsorbing vessel over the hot reactivated tower, from top to bottom.
The blower (5) takes ambient air and blows it over the external heater (6). The heated air is then sent through the saturated desiccant (2), forcing the adsorbed moisture out, from bottom to top.
Blower purge desiccant dryers (with and without zero purge cooling):
Heatless dryers use a small portion of the dried compressed air for regeneration. Heated purge dryers use a small and heated portion of the dried compressed air for regeneration. Blower purge dryers use heated ambient air for regeneration.
Blower PurgeHeated PurgeHeatless
10 years life cycle cost
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Dry and clean compressed air is essential for a broad range of industrial applications. Yet it must be produced reliably, energy-efficiently and cost-effectively. Atlas Copco’s desiccant dryers protect your systems and processes. Their robust design ensures they operate with total reliability and deliver a constant, stable dewpoint in full load conditions and even during a temporary overload.
Complete protection and energy-efficiency for your application
Electronics Exceptional reliability for critical processes
Oil & Gas 100% availability in a demanding environment
Food & Beverage A reliable supply of dry air
Pharmaceuticals A tight control on quality
Dry air is used to remove microscopic debris from the surfaces of computer chips and boards. Moisture can play havoc with sensitive processes and cause oxidation of micro-terminal strips, resulting in product failure. The electronics industry needs desiccant dryers offering a dewpoint as low as -70°C/-100°F , 24/7 availability and maximum uptime.
Moisture-laden air is unacceptable for the oil and gas industry, particularly on offshore establishments. It causes rust and pipe scale that can clog orifices, foul transmitters and other delicate sensing equipment, and distort instrument readings. If tools become rusty or corroded they soon become inoperable, and replacements are expensive. Oil & gas installations need 24/7 availability of dry compressed air at a low dewpoint.
The presence of moisture during the preparation of foods and beverages can cause contamination of end products. Processing machinery can also be affected by moisture, which interferes with their operation and obstructs the free and easy movement of the ingredient or item of food.
Strict moisture control is a key factor in the manufacture of most drugs and medicines. Many materials used to produce pharmaceuticals have a physical affinity for moisture, which can cause powdered material to aggregate. Other powders that are formed into a tablet under high pressures will adhere only when in a dry state. Humidity can cause a tablet to crumble or the drug to decompose and diminish in its therapeutic value. To assure consistently high-quality drugs, the presence of dry air in the processing area and machinery is therefore vital.
Easy installation and long maintenance intervals The dryers have a small footprint thanks to an innovative all-in-one design. Delivered ready for use, installation is straightforward, minimizing costly production downtime. All internal components are easily accessible to facilitate maintenance. The use of high-grade desiccant and durable valves extends maintenance intervals beyond the standard three years.
Protecting your reputation and production Compressed air entering the air net is always 100% saturated. When it cools, this moisture will condense, causing damage to your air system and finished products. Removing moisture from compressed air with a pressure dewpoint as low as -70°C/-100°F, Atlas Copco desiccant dryers eliminate system failures, production downtime and costly repairs.
Assuring your peace of mind Through continuous investment in our competent, committed and efficient service organization, Atlas Copco ensures superior customer value by maximizing productivity. With a presence in over 160 countries, we offer professional and timely service through interaction and involvement. Uptime is guaranteed by dedicated technicians and 24/7 availability.
Driving down energy costs Atlas Copco’s desiccant dryers incorporate a range of energy-saving features that will cut your carbon footprint. A low pressure drop below 0.2 bar/2.9 psi drives down energy costs. Dewpoint sensing and control adapts the energy consumption to the real load of the dryer. An adjustable PDP setpoint enables you to adapt the dryer to your actual needs. A zero purge variant, with closed loop cooling, provides even further savings by consuming no compressed air at all.
Keeping your production up and running
Key features of Atlas Copco’s desiccant dryers ensure maximum uptime for production processes:
A constant Pressure Dewpoint (PDP) down to -70°C/-100°F at 100% load conditions is the result of large pipes and vessels and efficient regeneration.
A proven, durable design for the switching valves, the most important moving components in the dryer, significantly improves the dryer lifetime.
An advanced control and monitoring system takes continuous care of the dryer to ensure production efficiency.
Atlas Copco desiccant dryers meet or exceed the international standards for compressed air purity and are tested according to ISO 7183:2007. Naturally, all our dryers are IP54 compliant, providing full protection of electrical components, controls and displays.
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